2024 年 34 巻 2 号 p. 81-88
We developed a method to determine the absolute pressure effect on thermocouple electromotive force, based on a single wire method using Kawai-type multi-anvil apparatus. In this method, pressure conditions along the wires were evaluated based on in situ X-ray diffraction using synchrotron radiation. The pressure effect of the Seebeck coefficients for materials of type K, D, and R thermocouples were determined up to 16 GPa and 1173 K. The difference between the nominal and real temperatures was large especially for type R (−75 K at 13 GPa and 873 K). Recent technical developments enabled to conduct similar measurements above 20 GPa. The accurate evaluation of error in thermocouple nominal temperature would be highly important in many research fields including geophysics.
